Put pork in a baking dish then pour the butter or olive oil (making sure both sides are coated) and generously season.

Bake at 450 for 30 minutes, depending on the thickness of your tenderloin.

To make the sauce, heat the apple, thyme, lemon zest and water over a low heat for 15 minutes, cover and stir occasionally. The apples should break down to form a paste. Keep it warm and serve over pork.

I love apple with pork tenderloin. I adapted a stuffed tenderloin recipe with leek and apple and make a sauce, like yours, to serve on the side/top of tenderloin or chops. Leek + apple + thyme = good combo.